In July MPs heard local police commissioner Ian Johnston had accused former chief constable Carmel Napier of manipulating the figures.

Mrs Napier strongly denied this, after the force recorded the largest fall in crime in England and Wales in 2011-12.

Mr Johnson said a internal report looking at the recording of crime figures was in progress.

Mrs Napier quit as chief constable in June after an order from the commissioner to "retire or be removed".

On Wednesday Mr Smith said an inquiry was needed to ensure police performance indicators were credible to the public.

The MP was speaking before leading a Westminster Hall debate on the powers of police and crime commissioners (PCCs).

It's in everybody's interest that we have police performance indicators that are credible to the publicNick Smith, Blaenau Gwent MP

"Mr Johnston has had a troubled first year in office but questions still remain with key issues like the resignation of the former chief constable," he said.

"Mr Johnston has queried the police performance figures, so let's have an external take on whether or not the crime figures in Gwent were correct.

"It's in everybody's interest that we have police performance indicators that are credible to the public."

Inspectors' visit

Mr Smith said HM Inspectorate of Constabulary (HMIC) was due to visit the Gwent force before the end of the year as part of its National Crime Data Integrity programme and suggested this would be a "perfect opportunity" for HMIC to investigate claims that crime figures had been "capped".

Mr Johnston said in a statement: "In response to the debate initiated by Nick Smith MP about the powers of police and crime commissioners in Wales, I can confirm an internal interim crime recording report was commissioned in July.

"An update on progress was presented to the strategy and performance board on September 17th and is available on the police and crime commissioner website.

"The full report will be presented to the Police and Crime Panel in due course as they are the body that holds the PCC to account."

Gwent Police said the matter was a PCC-led issue and the force had nothing to add.

Meanwhile the Gwent Police and Crime Panel is due to confirm Mrs Napier's deputy Jeff Farrar as her replacement on Friday.

A police officer for 29 years, Mr Farrar is Mr Johnston's proposed candidate for the top job and was the only applicant.